Ori and the Will of the Wisps

Works fine in 21:9.
32:9 pillar-boxed to 21:9 aspect ratio.

Fix for 32:9 and Surround/Eyefinity:

Make sure you run the game at least once.

Step 1:
HEX edit Aspect Ratio: Go to --> ...\Steam\steamapps\common\Ori and the Will of the Wisps\GameAssembly.dll
Look for 60 E5 18 40 and change it to 00 00 10 41. (This will nop some instructions and tell the game to disable letterboxing).

Step 2:
Open Regedit and navigate to Computer\HKEY_CURRENT_USER\Software\Moon Studios\OriAndTheWilloftheWisps
Find the key (or close to) Screenmanager Resolution Width_h182942802 and set the resolution you want for the Width. (Make sure to select decimal and not hex when you write it).
Do the same for the Height (there is an obvious key for it as well).

Start the game and enjoy!

Cheers,
Helifax

Everything is limited to 21:9 Aspect Ratio.

See Ultra/Super-Wide Specific Solution above.